The related art discloses an absorption heat pump apparatus or the like that performs an air heating and cooling conditioning operation by using a large quantity of absorption liquid capable of absorbing refrigerant vapor which is formed due to the evaporation of a refrigerant, and by using the heat of vaporization of the refrigerant and the heat of condensation of the refrigerant (for example, refer to JP 4-236079A (Reference 1)).
JP 4-236079A (Reference 1) discloses an absorption refrigerator (absorption heat pump apparatus) that includes a regenerator, a condenser, an evaporator, and an absorber. In the absorption refrigerator disclosed in JP 4-236079A (Reference 1), the absorber is provided with a heat exchanger which has a circular arc-shaped heat transfer surface which is convex upward, and through which cooling water flows; blades (coating member) that have a rotating shaft disposed opposite to the circular arc-shaped heat transfer surface; and a nozzle that supplies a concentrated solution (absorption liquid) to a ceiling portion of the heat exchanger. With the configuration of the absorber, when the concentrated solution, which is supplied to the ceiling portion of the heat exchanger through the nozzle, flows naturally downward on the heat transfer surface, the blades rotate about the rotating shaft, and thereby the concentrated solution spreads over the heat transfer surface, and a uniform film is formed. Accordingly, the concentrated solution formed into a thin film is diluted by absorbing refrigerant vapor from the evaporator, and the heat of absorption produced by the dilution of the concentrated solution is taken away through the heat transfer surface by the cooling water. Refrigerant vapor is more absorbed by the concentrated solution cooled on the heat transfer surface. With the configuration of the absorber, the concentrated solution is spread over the heat transfer surface by the rotating blades, and is diluted by absorbing the refrigerant vapor, and then the concentrated solution is delivered directly to the outside of the absorber from a lower end portion of the heat exchanger through a diluted solution outlet.
In the absorber of the absorption refrigerator disclosed in JP 4-236079A (Reference 1), since the concentrated solution is spread over the heat transfer surface of the heat exchanger by the rotating blades, and is diluted by absorbing the refrigerant vapor from the evaporator, and then the concentrated solution is delivered directly to the outside of the absorber from the lower end portion of the heat transfer surface through the diluted solution outlet, there is a high possibility that the diluted solution may be sent (recovered) to the outside of the absorber while the refrigerant vapor is not sufficiently absorbed due to the stay of the diluted solution (absorption liquid) in the absorber for an insufficient period of time. At this time, in order to ensure the performance of the absorber (performance of the heat exchanger for cooling the absorption liquid), the following method may be implemented: a circulation pump (solution pump) and a solution circulation circuit are separately provided, and the absorption liquid flowing downward to the lower end portion of the heat exchanger is pumped upward and re-supplied to the ceiling portion of the heat exchanger. However, there is a problem in that the separate provision of the circulation pump and the solution circulation circuit leads to an increase in the size of the absorption refrigerator (absorption heat pump apparatus) including the absorber.